Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['u', 'a', '6393', '4067', 'O', '1479', '7807']

21, 1, 6393, 4067, 15, 1479, 7807